Fortification of soft drinks with protein from cottage cheese whey.

Abstract

Cottage cheese whey protein concentrates, prepared by preconcentration by ultrafiltration followed by gel permeation to remove low molecular weight materials, have the solubility, stability and flavor that make them suitable for fortification of soft drinks and related products. These concentrates are characterized by high levels of "available" lysine and by amino acid compositions indicating good nutritional value. Carbonated beverages prepared with conventional beverage ingredients and containing up to 1% by weight of the total beverage of added whey protein maintained clarity, color, and flavor during 203 days storage at room temperature. Spray dried whey protein concentrates were incorporated without adverse effects into commercial "ade" type powders. Clarity of 1% protein solutions at pH 2--3.5 was not impaired by heating for 6h at 80 degree, but some structural change occurred since an average of 37% of the protein precipitated on shifting pH to 4.7. Increased stability against heat denaturation under acidic conditions was conferred by some soft drink ingredients. Added sucrose reduced protein denaturation by 1/2 but sodium saccharin had no effect. The type of acid used also altered protein denaturation rate. While properly isolated whey protein concentrates have functional properties necessary for soft drink fortification, feasibility of use will depend upon cost.